/Engine/Plugins/Online/OnlineServicesEOSGS/Source/Public/Online/SessionsEOSGS.h
void AddAttribute ( EOS_HSessionModification & SessionModificationHandle, const [FSchemaAttributeId](API\Plugins\OnlineServicesInterface\Online\FSchemaAttributeId) & Key, const [FCustomSessionSetting](API\Plugins\OnlineServicesInterface\Online\FCustomSessionSetting) & Value )